Isolation and structure of a rhodopsin gene from D. melanogaster
Isolation and structure of a rhodopsin gene from D. melanogaster
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DOI：
10.1016/0092-8674(85)90344-7
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发表时间：
1985-04
期刊：
影响因子：
64.5
通讯作者：
C. Zuker;A. Cowman;G. Rubin
中科院分区：
文献类型：
--
作者：
C. Zuker;A. Cowman;G. Rubin
利用一种新的检测交叉同源核酸序列的方法，我们分离了果蝇主要视紫红质的编码基因，并将其定位于染色体9288-11区域。cDNA和基因组DNA序列比较表明该基因分为5个外显子。从核苷酸序列推导出的氨基酸序列长373个残基，多肽链含有7个疏水片段，似乎对应于其他紫红质的7个跨膜片段特征。果蝇视紫红质的三个区域与牛视紫红质的相应结构域高度保守，表明这些多肽区域具有重要作用。视紫红质是脊椎动物和无脊椎动物眼睛的主要光感受器8（综述见Fein和Szuts，1982）。它由共价连接到维生素A衍生的发色团（通常为1%的β-视黄醛）的脱辅基蛋白、视蛋白组成。视紫红质的光活化是将吸收的光子的能量转化为膜电位变化的复杂过程中的第一步。发色团通过光从11-顺式异构化为全反式构型，这反过来导致视蛋白部分的构象变化。然后，这种光活化的视紫红质分子触发导致受体电位的级联事件（Stryer，1984年综述）。牛和人视紫红质的基因已被分离出来，并确定了它们的核苷酸序列（Nathans和Hogness，1983，1984）。这些哺乳动物视蛋白都是348个残基长，并且在结构上高度同源。果蝇提供了一个有吸引力的实验系统，在其中研究光转导的分子基础。果蝇的复眼包含三种不同类型的光感受器（Pak和Grabowski，1978年综述）。在构成眼睛的大约800个小眼中的每一个中，存在六个外部（R1-R8）和两个中央（一个R7和一个R8）感光细胞。在R1-R8细胞、R7细胞和R8细胞中发现的色素在它们的吸收光谱中不同，最可能是因为在这三类光感受器中表达不同的视蛋白。已经鉴定了几个突变影响光转导的基因座（Hall，1982年综述），包括一个ninaE，其在1982年12月15日的突变中表达。
Using a novel method for detecting cross-homologous nucleic acid sequences we have isolated the gene coding for the maior rhodopsin of Drosophila melanogaster and mapped it to chromosomal region 9288-11. Comparison of cDNA and genomlc DNA sequences indicates that the gene is divided Into five exons. The amino acid sequence deduced from the nucleotide sequence is 373 residues long, and the polypeptlde chain contalns seven hydrophobic segments that appear to correspond to the seven transmembrane segments characteristic of other rhodopslns. Three regions of Drosophila rhodopsin are highly conserved with the corresponding domains of bovine rhodopsin, suggesting an important role for these polypeptide regions.Rhodopsin is the major photoreceptor of both vertebrate and invertebrate eye8 (reviewed in Fein and Szuts, 1982). It consists of an apoprotein, opsin, covalently attached to a vitamin A derived chromophore, generally 1% &-retinal. Photoactivation of rhodopsin is the first step in a complex process that converts the energy of an absorbed photon into a change in membrane potential. The chromophore is isomerized by light from the 11-cis to the all-trans configuration, which in turn leads to a conformational change in the opsin moiety. Such photoactivated rhodopsin molecules then trigger the cascade of events that results in a receptor potential (reviewed by Stryer, 1984). The genes for bovine and human rhodopsin have been isolated and their nucleotide sequences determined (Nathans and Hogness, 1983, 1984). These mammalian opsins are both 348 residues long and are highly homologous in structure. Drosophila provides an attractive experimental system in which to study the molecular basis of phototransduction. The compound eye of Drosophila contains three distinct classes of photoreceptors (reviewed by Pak and Grabowski, 1978). In each of the approximately 800 ommatidia that make up the eye there are six outer (Rl-R8) and two central (one R7 and one R8) photoreceptor cells. The photopigments found in the Rl-R8 cells, the R7 cell, and the R8 cell differ in their absorption spectra, most likely because different opsins are expressed in these three classes of photoreceptors. Several loci at which mutations affect phototransduction have been identified (reviewed by Hall, 1982), including one, ninaE, that ap-